Sensitized photographic cellulose ester silver halide emulsion



Patented Sept. 7, 19 4 8 ISENSITIZED PHOTOGRAPH) CELLULOSE ESTER SILVER HALIDE'EMULSION} Wesley G. Lowe and Itaii'e- Tarkington, Rochester, N. Y., assignors to Eastman Kodak New Jersey (lompanm'Rochestr, N. 1L, a. corporation of No Drawing. Appucancdmy'c, 1946,31" 4 Serial No. 681,766

This invention relates to photographic emulsions and more particularly to photographiccellulose ester silver halide emulsions. This application is substantially identical with and replaces our application Serial No. 426,486, filed January 12, 1942, now abandoned.

20 Claims. (01. 95-7) Photographic silver halide emulsions prepared I in solutions of far hydrolyzed cellulose esters are known (see, for example,United' States Patent 2,110,491, dated March 8, 1938.) However, such emulsions have hitherto been found to beonly of moderate sensitivity unless heat treatment to induce silver halide grain growth is used in their preparation, or unless nitrogen-containing peptizers (which permit the use of sulfur sensitizers) are used in the preparation of the emulsions.

Polyvinyl acetals in which a portion of the acetal groups are p-dimethylamino-benzaldehyde acetal groups are suitable nitrogen-containing peptizers. See United States Patent No. 2,276,322 dated March 17, 1942. However, the above methods of obtaining higher sensitivity have disadvantages, in that ordinary heat treatment or the use of nitrogen-containing peptizers produces emulsions of low contrast which are unsuitable for certain photographic work where high contrast is necessary, as in the case of the preparation of film for cine positive, microfile and other copying work. Thus, while gammas of 4 or 5 can be obtained readily on slow unripened emulsions, these same emulsions if ripened to higher speeds or if prepared with nitrogen-containing peptizers may increase their speed as much as fifty times or more, but show gammas of less than one.

We have now found that the speed of celluloseester-silver halide emulsions can be increased many fold while maintaining high contrast. It is, accordingly, an object of our invention to provide new and improved photographic celluloseester-silver-halide emulsions. A further object is to provide a process for preparing such emulsions. Other objects will become apparent hereinafter.

In accordance with our invention,'we prepare cellulose-ester-silver-halide emulsions in the presence of ethylene diamine. The speed of the emulsions is greatly increased owing to the ethylene diamine while the contrast of the emulsion remains high. Hydrazine and hydroxylamine have some slight action of this kind, but are markedly inferior to ethylene dianiine, monia is, of course, a ripening agent with cellulose-ester-emulsions as it is with gelatino-emul sions, but it lacks the ability to keep the contrast I 55 H and D speed flr m mu 0.1 Gamma..-

of thecellulose-ester-emulsicns up to the desired figure.

We have found that the presence of ethylene diamine makes possible the use of sulfur sensitizers in cellulose-ester: emulsions, l. e., in the presence of ethylene diamine, sulfur sensltizers, such as thiourea, thiocarbanilide, and especially alkali metal thiocyanates and ammonium thiocyanates, act to increase the speed of celluloseester-silver-halide emulsions even above the speed increases that can be obtained with ethylene diamine alone.

The following examples will serve to illustrate ourinvention.

i Example 1 Far hydrolyzed. cellulose acetate propionate of high viscosity, containing 19% to 33% by weightof acyl groups, was. dissolved in a 1:1 (volumes) acetone-watermixture to make an 8 /2 solution; by weight. 20 g. of this solution was diluted with. 40 cc. of water and cc. of ethanol, The re sulting mixture was warmed to 80 C. The fol-- lowing two solutions, A and B, both at 80 0., were. then allowed to run simultaneously into the aforesaid mixture over a period of three minutes while stirring rapidly:

(A) 20 cc. of -a"50% (by weight) aqueous 5,0111- tlon of silver nitrate. (B) 20 cc. of a 4() (by weight) aqueous spin tion of potassium bromide and 1. to. of a 25% (by weight) aqueous solution of potassium iodide.

of the aforesaid il /2% solution of cellulose: acetate propionate was then added to the resulting emulsion and thoroughly stirred into the emulsion. The emulsion was then precipitated by pouring into water, and the shreds thus: formed were freed of organic solvents and of excess-salts by washing with several changes of. water. The emulsion was then pressed to a. weight of g. and dissolved by stirring intothe following solvent mixture:

. C'c. water 11o Acetone 90 Monoethyl ether of ethylene glycol 50 Monoacetin 6 The emulsion'was then spectrally sensitized with 4 mg. of 2.3 -diethyl-4'-methyloxathiazolocarbocyanine iodide. The sensitized emulsion was then coated onto film. The emulsion showed the following properties:

developed for four minutes with Eastman Kodak Company D-16 developer.

Example 2 H and D speed 1.0 Gamma v 2,3 developed for four minutes with Eastman Kodalgg Company D46 developer.

Example 3 An emulsion likethatpf Examplefl wasiprepared,-but with 2 ccyof; a '10 %1(by weight) aquea, ous solution of potassium wth-iocyahate added! along with the ethylene; diaminei: After=;-sp,ec,-- v trally sensitizing and scoatlng,;theremulslonghada the; following properties: ;i

developed'fcr four minutes with- CompanyjD-IG developer.

Our invention is directed especially-ate the far; hydrolyzed cellulose-ester silver-halide emulsions containing from 19% to 33% by weight of acyl roups. Far.hydrolyzedcellulose.esterscontaining from*20% .to-,26-.% by weighttcfiacylzgroups; are most advantageously. employed; Cellulose: acetate and, acetate-1propionates.v are: especially. usefuL, Emulsions made from such celluloseses tors are described in-v United- States Patent; 2,110,491; datediMarch .'s,1-..193a-... Cellu1o'se:.esters..= hydrolyzed l to; an. acyl. group gcon'tenta of :below. i are, described inqvUnited States,Patents;-v l,896,145, dated February 'l; 193-3; and;;1;954,-336,- dated April 10, 1934. Cellulose esters hydrolyzed; to an acyl group content of below 30% are .de-. scribed inUnited States Patent '2,;1 29,052'-,; dated' September 6, 1938.

What we claim as 0ur invention and desire to be secured by Letters Patent, of ,the United HStates 1. A photographic silver halide emulsion in which the silver halide-lsdispersed in ,a hydro lyzcd cellulose carboxylic ester containingirom, 19 to 33 %,.by weightof acyl groups, saidemul sion containingiethylene diamine 5 2. .A photographic silver 1 halide: ,-,-emulsion .,in which the. silverv halide. is dispersedin rajhydro W lyzed cellulose .carboxylic ester containingl froml. 20% ,to 26% by weight ofacyl groups, said emul: sion containing.ethylenediamine. l

3. A photographic silver halide emulsion 1m; which the silver halide is dispersed in a hydrolyzed cellulose carboxylic ester containing from. 19% to 33% by weight of acyl groups, said emul-g sion containing eth l ne. iami e and, lthlopk anate selected from the group c-onsistingoi alkalh. metal and ammonium thiocyanates.

4. A photographic, silver. halideemulslon, which the silver halide is, dispfirfied inaa hydro; 1 lyzed cellulose, carboxyli'c, ester containing irom 20% .to 2.6% 'by Wei ht ofi-acy er u sp aidlemulasion containing ethylene diamineanda thiocy=- anate selected from the group consisting of alkali metal and ammonium thiocyanates,

A Pr e rw ncr s nat c pee o v 3:9;- v -9i an. Ko ak.

hea- 15 tographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose carboxylic ester containing from 19% to 33% by weight, of acyl groups, saidprocess comprising digestingstheemulsi-on in-the presence of ethylene diamine.

6. A process for increasing the speed of a photographic silver halide emulsion in which the silver-halide:,istldispersed in a hydrolyzed cellulose Lcarboxyl-icl ester-containing from 20% to 26% by weight of acyl groups, said process comprisin digesting-the. emulsion in the presence of ethylene namin '7. A processfonincreasing the speed of a photographic silver halide emulsion in which the silver halide-is-dispersed in a hydrolyzed cellulose 'carboxylic ester containing from 19% to 33% by weightpi acyl groups, said process comprising digesting the emulsion in the presence of ethylene dlamine and, a, thiocyanate selected, from the group CQ3' Si Sti I 1g, ;0i lk lilmet l and ammon m,- thiocyanates.

8.;Aprocess for increaslngtheispeed of a photo raphic silver halidei emulsion in whichthe si1 ver halide is dispersed in a hydrolyzedcellulose carboxylic estercontaining from 20%,tO,26% by weightlof;acylJgroups, said process comprising, digesting v f heeinulsion in the presence ofethylene, diamine and a thiocyanate selected from the group, consisting of alkalimetal and ammonium. thiocyanates. l.

9,. A photographi c.,.silver. halide, emulsion. in. which the ,silver, halide is dispersed ,in a hydro lyzed; cellulose acetate containing, from V 19 to; 33 by v weight of, acetyl vgroups, said emulsion containin e hyl ned amine- ,10. ,A photograph c silver -halide== emulsion in whichthe,., si-lver halideeisldispersed in a hydrolyzedcellulose. acetate containing from- 20% to 26% V. by, weight ,of, acetyl I groups, said emulsioncont ainingl ethylenediam-ine;

11., A photographic silver halide emulsion in; which the silver: halide. ,isdispersed in a hydro-1 lyzed cellulose, acetate: propionate, containing from.l9 to, 33% by. weight of acylgroups, saidemulsion .containing ethylene r diamine.

12.,,A photographic:- silver; halide emulsion inwhichthe-silver halide-is dispersed-in a hydro-. lyzed cellulose acetate propionate; containing said;emulsion ,containingsethylene diamina; V

13.-A, photographic, silver halide emulsion in which ,the silver; halide-is dispersed in -a hydro V. lyged, -.cell ulose acetate propionate; containing from 49%, to 33 -by-weightof acyl-groups; said: emulsioncontaining ethylenediamineand a'thio-g cvanat ected. r the oup co sisting of. a1- kal e eli ndaamm ium,th o vanates.

14.." A: photographic? SllVeI hBJldB emulsion in 1 which. .thesilver-halide is ,dispersedin a-,.hydrolyzed-scellulose: acetate; propionatev containin from 20% to 26% by Weight of acyl groups; said emulsio -vn a n nsa h leneld amineandathim yen t zs ec e -zf m h r p on stinsnof a1:

15wA precess for -in creasing the speed: of; a. photographic: silver: halide. emulsion -inwhich the silver halide is;.dispersed; in ahydrolyzed eelluloseg acetate,eontaining from 19- ,tov 33% ,lby weightpf: cetyl gr uper ,s i -pro ss mp s nezdi-sest ns theemulsion inthe presence of ethylene'diamine;

ies-aproc ss nc e si s;..thesoeedfi a photo ra hic ii er a idezemi ls enam which the;

a siIVBR' M d iE dis ersed fin -hydr zed cellulosez:

acetate containing from 20 to 26% by weightgofii l acetyl groups, said process comprising digesting the emulsion in the presence of ethylene diamine.

17. A process for increasing the speed of a photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate propionate containing from 19 to 33% by weight of acetyl groups, said process comprising digesting the emulsion in the presence of ethylene diamine. V

18. A process for increasing the speed of a photographic silver halide emulsion in which the silver halide is dispersed in a hydrolyzed cellulose acetate propionate containing from 20 to 26% by weight of acyl groups, said process comprising digesting the emulsion in the presence of ethylene diamine.

19. A process for increasing the speed of a photographic silver halide emulsion in which the silver halide is dispersed in cellulose acetate propionate containing from 19 to 33% by Weight of acyl groups, said process comprising digesting the emulsion in the presence of ethylene diamine and a thiocyanate selected from the group con- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Sheppard et al. Dec. 19, 1939 Number 

